Jose Padilla was originally accused of planning a "dirty bomb" attack in the United States.

Co-defendants Adham Hassoun and Kifan Jayyousi were also found guilty of the three counts charged: conspiracy to murder, kidnap, and maim people in a foreign country; conspiracy to provide material support for terrorists; and providing material support for terrorists.

Padilla was originally arrested on accusations that he planned to set off radioactive "dirty bombs" in the United States. Thursday's convictions are not related to those accusations, and prosecutors did not present the "dirty bomb" plot to the jury.

All three defendants face life in prison when they are sentenced on December 5.

Attorney General Alberto Gonzales -- who is on vacation this week -- issued a statement saying, "The conviction of Jose Padilla -- an American who provided material support to terrorists and trained for violent jihad -- is a significant victory in our efforts to fight the threat posed by terrorists and their supporters."

Padilla received a "fair trial and a just verdict," the White House said in a statement.

"We commend the jury for its work in this trial and thank it for upholding a core American principle of impartial justice for all," the statement said.

Defense attorneys argued at trial that Padilla went overseas only to study Islam.

Padilla's mother, Estela Lebron, told CNN her son will appeal the verdict.

"I'm not surprised by anything in this place anymore," she said. "This is a Republican city."

Lebron blamed President Bush for the outcome of the trial and said there was not enough evidence in the case to convict her son.

Attorneys for the other defendants also vowed to appeal, saying they were "stunned" by the decision.

"An innocent man was wrongly convicted today and we're going to do what we can to clear his name," said William Swor, the attorney for Jayyousi.

"We're all stunned ... because Dr. Jayyousi is innocent, because there was no evidence presented except pieces of conversations spun from another language that have so many different meanings.

"We're going to fight to get him released," he added.

Padilla attorney Anthony Natale declined to comment on the outcome.

The verdict is a "critical vindication" for the U.S. Department of Justice and its post-9/11 strategy for prosecuting terrorism cases, said Kendall Coffey, former U.S. attorney in Miami who comments on legal matters for CNN.

"I think this is huge for DOJ," he said, "given the case's background of controversy and the government's mixed results in other (terror) trials."

He said the verdict also raises questions about whether military tribunals are necessary.

"Critics of the post-9/11 war on terrorism can point to this and say you don't need military tribunals, you can get the job done with civilian trials," Coffey said.

During the trial, prosecutors played more than 70 intercepted phone calls among the defendants for jurors, including seven that featured Padilla, 36. He is a Brooklyn-born convert to Islam.

FBI agent John Kavanaugh testified that the calls were made in code, which Padilla used to discuss traveling overseas to fight with Islamic militants, along with side trips to Saudi Arabia and Afghanistan.

In closing arguments, Padilla's lawyers argued he never spoke in code. His voice is heard on only seven of 300,000 taped conversations.

They also tried to rebut a key piece of prosecution evidence -- an al Qaeda terrorist training camp application or "mujahedeen data form."

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A covert CIA officer -- who testified in disguise at Padilla's trial -- said he was given the form in Afghanistan, and a fingerprint expert found Padilla's prints on the form, prosecutors said.

"The al Qaeda application virtually sealed his fate," said Jonathan Turley, a professor at George Washington University Law School. He compared the document's value as evidence to "putting a duffle bag with severed heads on the table."

But Michael Caruso, Padilla's defense attorney, said the prints on the form were not consistent with someone who filled out the document.

"Jose at some point handled the document, but did not fill out the form," Caruso said.

Just as prosecutors did not present the dirty bomb plot to the jury, neither were jurors told that Padilla was held in a Navy brig for 3½ years without charges before his indictment in the Miami case.

Turley said the case was troubling because it appears Padilla was kept in the brig in violation of his rights, for no legitimate reason.

"The evidence changed very little in the 3½ years Padilla was held without charges or access to a lawyer as an 'enemy combatant,' " he said.

Before trial, his lawyers tried to argue that he was no longer mentally competent to stand trial after years of solitary confinement and abuse -- allegations the government strongly denied.

Padilla was taken into custody in Chicago as he stepped off a flight from Pakistan in 2002, and Bush declared him an "enemy combatant" and had him transferred to military custody. He was never charged as an "enemy combatant" and was eventually transferred from military to civilian custody where he was finally charged.

The Supreme Court ducked the chance to rule on the legality of Padilla's military detention in 2006, arguing that the issue was moot after his transfer to civilian custody for the Miami trial. E-mail to a friend